1. Field of the Invention
The invention relates to a photosensitive resin composition and a thin film and apparatus formed thereby; particularly, to a photosensitive resin composition for producing a product having good high-temperature resistance and high-humidity resistance.
2. Description of the Related Art
In the manufacturing process of a liquid crystal display component, forming an overcoat on a substrate is an important step. Demanding procedures under harsh conditions are required for manufacturing a liquid crystal display component or a solid-state imaging device, etc. For example, local high temperature occurs when processing by infusion with an acid solvent or alkaline solvent on the surface of substrate or by sputtering to form a wiring electrode layer. Thus, an overcoat is needed to be laid on these components to prevent them from damage. Nowadays, the overcoat is generally made of photosensitive resin by means of coating, exposure and developing, etc.
To enable the overcoat to resist the aforementioned processing, high transparency, high surface hardness and smoothness is required, along with an excellent adhesive force between the overcoat and substrate. Moreover, good water-proofing and strong resistance to solvents, acid and alkali, etc, of the overcoat is also required. In the foregoing characteristics, since the overcoat is formed on a color filter or a substrate, the requirement of high transparency is critical. If the transparency of the overcoat is poor, when applied to the liquid crystal display element, the brightness of the liquid crystal display element is insufficient, and the display quality of the liquid crystal display element is impacted.
To improve the transparency of the overcoat, Japanese Patent Publication No. 2010-054561 disclosed a photosensitive composition for an overcoat, comprising: an alkali-soluble bonding resin (A); an ethylenically unsaturated compound (B); a light initiator (B); and a solvent (D); wherein the bonding equivalent of the unsaturated bond in the ethylenically unsaturated compound (B) is between 90 and 450 g/eq, and the amount of unsaturated double bond of a single compound is between 2 and 4 in the ethylenically unsaturated compound (B); and the average molecular weight of the alkali-soluble bonding resin (A) is between 10,000 and 20,000. Additionally, Japanese Patent Publication No. 2004-240241 has disclosed a photosensitive composition comprising: a copolymer (A), which is polymerized by an ethylenically unsaturated carboxyl (anhydride), an ethylenically unsaturated compound containing an epoxy group and other unsaturated ethenyl compounds; an ethylenically unsaturated ethenyl polymer (B); and a photoinitiator (B). The photoinitiator (B) is 2-butanedione-[-4-methylthio benzene]-2-(O-oxime acetate), 1,2-butanedione-1-(-4-morpholino phenyl)-2-(O-benzoyl oxime), 1,2-octadione-1-[4-thiophenyl benzene]-2[O-(4-methyl benzoyl) oxime] or its analogue. Though the photosensitive composition is able to fabricate an overcoat of high transparency, it presents the poor temperature resistance and humidity resistance.
Therefore, a photosensitive that enhancing the temperature resistance, humidity resistance and transparency of the overcoat at the same time is a target remained to be achieved.